The present invention relates to the combustion control system of a gasoline engine, and more particularly to the closed loop control device of a two-stroke gasoline engine.
The operators of the automobiles have become increasingly concerned with the operating efficiency of the cars and the air pollution brought about by the operation of the cars. That is to say that the driving public is focusing the attention on the standard of exhaust fume and the efficiency of combustion. Of course, an efficient combustion of fuel in a car engine will produce the exhaust fume which is less likely to pollute the air in our environment. Such goal can be achieved by improving the precision, with which the ratio of air and fuel mixture is controlled. The fuel supply system, either a carburetor or a fuel injection system, of the conventional two-stroke gasoline engine has two major defects, which are further expounded hereinafter.
The conventional two-stroke gasoline engine is not provided with the closed loop control device capable of automatically adjusting the air fuel ratio with precision in accordance with the quality of the exhaust fume. In addition, the efficient combustion of fuel in such engine can be adversely affected by the incidents such as the carbon deposit in exhaust holes, the dirty air filter, and the deterioration of work quality of the fuel controlling element, when such engine becomes older.
Unlike a four-stroke gasoline engine, a two-stroke gasoline engine is not provided with means which prevents the feeding process of the air-fuel mixture and the discharging process of fume from taking place almost simultaneously during the same stroke of a piston and which prevents the short circuit of the gas vapor from developing. As a result, the fume exhausted from such two-stroke gasoline engine is often combined with some of the fresh air-fuel mixture fed into the engine and is therefore not suitable to be analyzed for the purpose of determining the conditions under which air and fuel are mixed and burned in the combustion chamber so as to feed back such information for adjusting the optimum air-fuel ratio.